After passing a physical, Kaminsky, an 18-year-old left-handed pitcher out of St. Joseph Regional (N.J.) High School, signed his contract Tuesday at Busch Stadium. He will begin his Minor League career in Jupiter, Fla., with the Gulf Coast League Cardinals, who begin their season Saturday. Second-round Draft pick Oscar Mercado, who officially signed Monday, will also start his career there.

"Two of our three top picks are young high school players, so that's the age-appropriate league for them," said scouting director Dan Kantrovitz.

Kaminsky turned down a scholarship to play baseball at North Carolina to join the Cardinals. He signed for a $1.7853 million bonus, the slotted amount for the No. 28 pick.

"It was tough. I liked North Carolina, but my parents always said that one thing supersedes a college education at that institution and it was playing professional baseball," Kaminsky said. "I kind of knew for a long time I wanted to play, and when the dream became a reality, I couldn't pass it up."

Kaminsky's best pitch is his curveball, which he says he is confident using in any situation, but he added that his changeup isn't far behind. He is fresh off an excellent senior campaign, in which he went 9-0 with 118 strikeouts and five walks in 58 innings. While he played in a region that isn't known for its visibility, Kaminsky took advantage of summer showcases to impress big league scouts.

Kaminsky's height (or lack thereof) was the biggest knock on the first round prospect.

"I've been told I can't get people out because I'm 6-foot," Kaminsky said. "But ... I don't think you have to be a certain height to get people out."

The left-hander counts Cardinals catcher Yadier Molina among his favorite players and said he's excited to join an organization with a strong reputation for developing elite pitching talent, another factor that helped lure him away from his commitment to North Carolina.

"This is a tradition," Kaminsky said. "They let you be you. Just the organization speaks for itself, to be honest. I don't have to comment much on that. It's just the winning tradition, and I love it. And it's just a great feeling."

Chad Thornburg is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.